Increasingly, many industrial, commercial, and public infrastructure applications have utilized light emitting diodes for lighting. Compared with previous lighting techniques such as incandescent or fluorescent lighting, LEDs can provide, a broad color spectrum, compact size, increased energy efficiency, absence of mercury and related environmental concerns, increased operating life, ability to dim output, absence of infrared or ultraviolet spectral components (when desired), and low voltage (on a per LED basis).
The emergence of high brightness light emitting diodes (HB-LEDs) may have improved aspects of solid state lighting solutions, which may provide performance advantages over conventional lighting technology. Higher optical efficiency, long operating lifetimes, wide operating temperature range and environmentally friendly implementation may be some of the key advantages of LED technology over incandescent or gas discharge light source solutions. However, manufacturing variations in forward voltage drop, luminous flux output, and/or peak wavelength may necessitate binning strategies, which may result in relatively lower yield and increased cost. Furthermore, a large number of LEDs, with matched characteristics, arranged in a suitable optical housing, may be required to meet the desired optical and luminance performance requirements. Dimming requirements and the need for circuit compensation techniques to regulate light output over a range of temperatures, and lifetime of the hardware may render a resistor biased drive solution obsolete for modern LED.
Various circuit techniques based on switching and linear regulating devices may have been described for driving a single “string” of series LEDs with precise forward current regulation and pulse modulation based dimming techniques. Such architectures may require a dedicated drive circuit for each LED string, and therefore may not be suitable for controlling a large number of strings.
It is within this context that embodiments of the present invention arise.